Driver assistance systems that support the driver in longitudinal and/or transverse guidance or independently perform longitudinal and/or transverse guidance are known, e.g., ACC (Adaptive Cruise Control), LDW (Lane Departure Warning), ISA (Intelligent Speed Adaption), or lane detection systems.
The essential task of such systems consists in reliably detecting the course and the lateral boundaries of the used lane, particularly in reliably (i.e., particularly at a low rejection rate) identifying traffic signs with regard to the ISA function.
From DE 103 11 240 A1 a vehicle tracking device is known, in which markings that delimit the pavement or the lanes are detected and evaluated by means of an environment sensor system and by means of evaluation means, wherein country-specific marking regulations for pavement marking are stored in a memory device. A navigation device by means of which the position of the vehicle is determined is provided for using these data.
Furthermore, in the method known from DE 103 43 941 A1, the changing traffic regulations are outputted after the crossing of a national boundary or when a national boundary is going to be crossed. This comprises, e.g., a regulation for a light control of the vehicle or a regulation for a speed limit of the vehicle. The position of the vehicle is determined by means of a navigation device (particularly by means of a satellite) in this known method as well.
A method for traffic sign recognition including the additional use of navigation data is known from, e.g., EP 1 114 371 B1. In this method, traffic signs are recognized in a first step, whereafter vehicle-locating navigation data are provided that are compared with each other and, if necessary, updated. For this purpose, these data are fed to an evaluation unit, a currently valid speed limit is determined, and, if necessary, control signals for a driver assistance system are generated.
However, these known methods or systems do not satisfactorily solve the problem of driver assistance systems having to adapt to country-specific features, which concerns, e.g., lane detection systems (e.g., LDW) or traffic sign recognition. For example, the recognition performance of the classifiers used in traffic sign recognition systems could be improved if a piece of information about the country in which the vehicle is traveling were available. Lane detection algorithms could also benefit from such a piece of information by using it, e.g., to eliminate any ambiguities with regard to pavement markings.